We present the validation of a water vapour dataset obtained by the Airborne Microwave
Stratospheric Observing System AMSOS, a passive microwave radiometer operating at 183 GHz.
Vertical profiles are retrieved from spectra by an optimal estimation method. The useful vertical
range lies in the upper troposphere up to the mesosphere with an altitude resolution of 8 to 16 km
and a horizontal resolution of about 57 km. Flight campaigns were performed once a year from 1998 to
2006 measuring the latitudinal distribution of water vapour from the tropics to the polar regions. The
obtained profiles show clearly the main features of stratospheric water vapour in all latitudinal regions.
Data are validated against a set of instruments comprising satellite, ground-based, airborne remote sensing
and in-situ instruments. It appears that AMSOS profiles have a dry bias of 0 to –20%, when compared to
satellite experiments. Also a comparison between AMSOS and in-situ hygrosondes FISH and FLASH have been performed.
A matching in the short overlap region in the upper troposphere of the lidar measurements from the DIAL
instrument and the AMSOS dataset allowed water vapour profiling from the middle troposphere up to the mesosphere.